1. Field of the Invention
The subject invention relates to a cold static gasket of the type for sealing two mating surfaces over a complex geometrical contact region, and more specifically toward a dual-durometer gasket having a resilient rubber sleeve of a first hardness and a core of resilient rubber material having a different hardness than the sleeve.
2. Related Art
Cold static gaskets are used in many applications in which two mating surfaces are required to be sealed over their contact region. A cold static gasket is distinguished from a hot static gasket in that it is not intended for use in extreme heat situations. Although cold static gaskets can be used in almost any field of endeavor. One example of a cold static gasket as used in the vehicular engine field may include an oil pan gasket, a transmission pan gasket, an engine-to-water pump gasket or the like.
In some applications including, but not limited to those exemplary engine applications described above, the contact region between the two mating surfaces to be sealed comprises a complex geometric shape. In other words, the contact region is non-circular, and may or may not include sharp bends, twists and three-dimensional formations. More complex geometrical contact regions can be especially challenging to seal over the life or intended service interval of the cold static gasket. Joint failures are particularly common in areas where the cold static gasket makes sharp bends or curves.
U.S. Pat. No. 3,660,192 to Smith et al., issued May 2, 1972, discloses a circular sealing ring having a resilient core. In this example, a PTFE tube is joined end-to-end and then injected with a liquid silicone rubber composition which eventually solidifies to form a resilient core. In this example, the PTFE tubing acts as a stiff exoskeleton and can be shaped around a mandrel into a desired form, preferably circular. The rigid PTFE tubing then operates like a mold holding the core in a defined shape until it is solidified to form a dual-durometer cold static gasket.
By contrast, U.S. Pat. No. 4,741,542 to Kimerly, issued May 3, 1988, discloses a cold static gasket for sealing a curved aircraft windshield against the fuselage. In this example, a hollow gasket sleeve is placed into an operative position between the windshield and fuselage and held in place by fastening elements. A silicone elastomer or other type of liquid rubber compound is then injected into the hollow interior of the sleeve thereby causing it to expand in the space between the adjacent part surfaces as the injected material cures. This in situ application requires the gasket to be formed in position on an actual aircraft. This is a particular disadvantage because the gasket assembly cannot be constructed in a factory setting and then shipped to another location for installation.
Accordingly, there exists a need for forming a shaped gasket of the type for sealing two mating parts over a complex geometrical contact region that is convenient to mass manufacture in factory settings, inexpensive and suitable for a variety of applications. Likewise, there exists a need for a shaped gasket of the type for sealing two mating surfaces over a complex geometrical contact region.